In modern construction, window and door systems generally are provided as integral pre-hung units that include door or window panels pre-mounted in a frame. The frame typically is formed by vertical jambs, a top header, and a bottom sill or threshold assembly that spans the bottom ends of the jambs. These pre-hung units are fitted and secured within appropriately sized framed-in openings in the walls of a building. In the case of windows, the openings generally are framed by a horizontal bottom sill plate, vertical studs, and a header. Framed-in openings for pre-hung door units also include vertical studs and a header, but the bottom sill plate of the door opening usually is formed by the sub-floor of the building. In either event, the pre-hung unit is positioned with its sill or threshold resting on the bottom sill plate of the framed-in opening, whereupon the unit is leveled, plumed, and secured within the opening with nails or screws.
An age-old problem with window and door units is the tendency, over time, for rain water to leak beneath the sill or threshold of the unit. Such leakage often occurs at the lower corners of the unit where the jambs meet the sill, but also can occur in mid-portions of the unit as a result of cracking or separation of sill components. Eventually, this leakage causes the underlying framing studs and sub-floor components to rot. Since this rot generally is hidden from view, it often is not discovered until it is so severe that major renovation to replace rotted members is required.
To address the problem of rain water leakage around windows and doors, building products suppliers have developed water-proof sill pans. These sill pans generally are designed to be installed in a framed-in window or door opening extending along and covering the bottom sill plate of the opening. Most prior art sill pans are made of plastic and include a central web that rests on and spans the plate, upwardly projecting end walls that extend partially up the vertical studs of a framed-in opening, an up-turned flange extending along the inside edge of the web, and flashing strips that wrap around onto the outside of the framed-in opening. In some cases, flashing pans are integrally molded from a single piece of plastic. In others, end pieces of molded plastic are installed in the bottom corners of a framed-in opening and a separate elongated central web is installed along the bottom plate with its ends partially overlapping the end pieces. The overlapping ends of the web are then secured to the end pieces with, for example, PVC cement or other adhesive. In any event, the purpose of a sill pan is to intercept rain water that may leak beneath a window or door unit and to prevent that water from soaking into wooden framing members and sub-floor components, thereby to prevent the rotting of these structures. Examples of prior art sill pans can be found in U.S. patents including U.S. Pat. No. 6,098,343 of Brown, and U.S. Pat. No. 6,401,402 of Williams. Prior art sill pans of the types discussed above are available from a number of building products suppliers, including Dinesol Building Products Ltd. of Youngstown, Ohio and Jambsil, Inc. of Talent, Oreg.
While prior art sill pans have been somewhat successful, they nevertheless have been plagued with a variety of problems and shortcomings inherent in their respective designs. Single piece molded sill pans, for instance, rarely fit precisely between the vertical jambs of a framed-in opening. This results in gaps between the ends of the sill pan and the jambs or in creases in the plastic of the pan, which can allow rainwater to seep beneath the sill pan and into the framing members below. Multiple piece sill pans result in a good fit between the jambs, but suffer from poor adhesive coverage and thus poor seals between the ends of the center web and the end pieces, which they overlap. Poor seals can result, in part, from the requirement in some systems that the overlapping portions be held together for 5 or more minutes as the adhesive sets. Installers are unlikely to follow these instructions, resulting in poor and leaky adhesive joints and thus poor seals. These poor seals allow water to seep through the adhesive joints and into the framing members below. Further, in both of these sill pan designs, water that is intercepted by the sill pan can collect between the sill pan and the wooden sill of windows, which can result in rotting of the window sill itself.
Another problem with prior art sill pans, especially when installed beneath door units, is that the constant jostling of the threshold of the door unit as it is repeatedly stepped on during use can wear through the material of the pan at locations where the door unit rests on the pan. This is particularly true for metal door units. At least one manufacturer has attempted to address this problem by providing an aluminum cladding bonded to the surfaces of the sill pan in areas of door unit contact. This solution, however, is expensive, not always successful, and can result in an unpleasant clicking sound when stepping upon the threshold.
A continuing need exists for an improved sill pan system that successfully addresses the above and other problems and shortcomings of existing prior art seal pans. It is to the provision of such a sill pan system that the present invention is primarily directed.